Noise
AFSCME members may be exposed to dangerously high noise levels in a variety of jobs and in virtually every workplace. Whether the job is a clerical position in an office environment, a heavy equipment operator in a landfill, or a lab worker in a hospital, noise is everywhere and Noise-Induced Hearing Loss is a serious consequence to the health of AFSCME members.
Hazards of Noise
Hearing Loss
Intense noise may result in temporary or permanent hearing loss.
Temporary Hearing Loss may be caused by exposure to noise. Normal hearing returns after some period of time. This recovery period may be only minutes or it may be hours, days, or even longer, depending upon the individual and the severity and length of the exposure.
After a day in an excessively noisy environment, workers may experience temporary hearing loss when the nerves in the inner ear become tired and strained and fail to send messages to the brain. Normal hearing will return if they remain in a quiet environment and allow their hearing to recuperate.
Permanent Hearing Loss, on the other hand, may occur from exposure to intense noises for an extended period of time without protection. IT IS PERMANENT AND CANNOT BE HELPED BY A HEARING AID OR SURGERY. Since hearing loss occurs gradually, many workers may not realize that they have permanently lost some of their hearing until it is too late.
Other Health Effects
Noise also affects health in other ways. It causes stress and increased blood pressure, and may contribute to heart disease and ulcers. Working in a noisy environment for long periods of time can make workers tired, nervous, and irritable, and has also been linked to insomnia and loss of appetite.
Noise may also be a safety hazard. It interferes with talking and hearing on the job. Difficulties with communication can cause accidents in the workplace. Prolonged intense noise causes fatigue which may also lead to accidents.
Measuring Sound
You don't need complicated equipment to tell if you are exposed to noise levels that could damage your hearing. You may be exposed to dangerously loud noise if:
- it is too noisy at work to be heard by co-workers at arms-length;
- it's hard to hear normal conversations, TV or music at the end of a working day;
- you get a ringing in your ears after working in noisy areas.
- family and friends notice that your hearing is less acute.
Sound level is measured with a sound level meter and is expressed in terms of decibels. The decibel, abbreviated dBA, is the unit of measurement used to measure noise.
It is important to understand that the decibel scale is not an arithmetic scale. Rather, it is a logarithmic scale. Most noise standards recognize a three decibel "exchange rate". The exchange rate is the decibel level that equals a doubling of energy and is also called a doubling rate. This means that an increase of 3 dBA is equal to doubling the sound pressure. At the same time, by reducing the sound pressure level by 3 dBA, the noise "dose" would be cut in half. Therefore, an increase or decrease of three decibels is significant.
In the OSHA standard, a five decibel "exchange rate" is used. That is, an increase of five decibels results in a doubling of the energy of the noise. And a reduction of five decibels results in halving the "dose".
Continuous, Intermittent and Impact Noise
A continuous noise is a sound which is relatively constant. An intermittent noise, on the other hand, is one which has perceptible gaps between repetitions.
Impact noise is like a gunshot. Tools such as jackhammers, air driven tampers, and other pneumatic tools are the classic examples of equipment which generate impact noise. Impact noise is often more harmful to the human ear than continuous or intermittent noise.
Controlling Noise Hazards
Methods of reducing noise levels in the workplace include the use of engineering controls, work practices, and personal protective equipment as listed below:
- Decrease noise production at the source: Engineering controls can be used to decrease noise by enclosing or shielding noisy machinery, installing exhausts or mufflers on jackhammers or putting dampening materials or rubber linings on machine tools. Worn bearings should be replaced. Vibration isolation pads may be installed under the legs of noisy equipment to reduce noise generated by the equipment vibrating on a cement floor. When new machinery is purchased, make sure that it is quieter than old machinery. Improving or fixing exhaust mufflers and adjusting the engine to reduce vibration can reduce vehicle noise.
- Isolate the worker or enclose the source of the noise: In noisy vehicles, the holes and cracks in the operator's cab can be sealed with rubber or plastic and the cab can be insulated. Noisy computer printers may be enclosed with hinged, insulated covers which contain the noise generated.
- Install sound absorbing materials: Acoustical materials may be installed on walls and ceilings to absorb sound waves and minimize reverberation. Examples include acoustical ceiling tiles and acoustic wall panels.
- Increase the distance between the worker and noise producing equipment: By doubling the distance from the worker to the noise source, the noise levels may be reduced to one fourth. It is important to remember that this practice will not work in an enclosed room because of the tendency of sound to be reflected off walls, ceilings, and other flat surfaces.
- Maintain machinery properly: Tightening screws, oiling/greasing, aligning machine parts can help reduce noise.
- Administrative Controls: Rotate workers so that the time each worker spends in a noisy area is limited.
- Use personal protective equipment: If engineering controls or other actions listed above cannot reduce the noise, ear muffs or ear plugs should be used as a last resort. They are a last resort because they often don't work well, are worn improperly, are uncomfortable and can cause ear infections. Ear muffs are generally better than ear plugs. They reduce the most noise, are least likely to cause ear infections and they require the least personalized fitting. Ear muffs can be worn with ear plugs to provide greater protection. However, ear plugs and ear muffs should be a last resort after other measures to reduce noise have been tried. OSHA also requires employers to provide training on the proper use of such equipment.
- Measure noise levels: Management and workers should monitor noise levels frequently in areas where noise seems to be high, to make sure that safe levels are not being exceeded or if there are any signs of Noise-Induced Hearing Loss. Monitoring is required under the OSHA standard (see below) where noise levels may exceed 85 dBA.
Workers have a right to witness the monitoring and should make sure that the noise is measured where people actually work and not in some other part of the area. Workers have a right to see the monitoring results. - Initiate a medical monitoring program: Workers exposed to noise levels over 85 dBA should receive "baseline hearing" tests when they begin work in a noisy area. Annual hearing checks can then be compared with the "baseline" to determine whether hearing loss has occurred. Such monitoring is required under the OSHA standard. Workers have a right to see the results of their exams.
The OSHA Standard (29 CFR 1910.95)
The OSHA noise standard limits noise levels to 90 dBA averaged over an eight-hour day, although hearing damage can begin at levels as low as 80 dBA over an eight-hour day. No worker may be exposed to noise in excess of 115 dBA without protection which will reduce the exposure below 115 dBA.
The following chart shows allowable exposure levels at various dBA which are all equivalent to a 90 dBA eight-hour average. For example, someone exposed to 95 dBA of noise could only be exposed for 4 hours.
The standard says that all areas suspected to be over 85 dBA must be monitored. If noise levels are above 90 dBA, your employer must first attempt to use engineering controls to bring noise levels down below 90 dBA before relying on personal protective equipment.
If your exposure exceeds 85 dBA averaged over eight hours, the OSHA standard requires your employer to provide you with annual hearing tests and a choice of free hearing protection. You are entitled to get a copy of the test results, and must be informed of any hearing loss.
For additional information on Noise and Noise-Induced Hearing Loss, contact your AFSCME staff representative.
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PERMISSIBLE NOISE LEVELS | |
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Duration of Exposure 8 6 4 3 2 1-1/2 1 1/2 1/4 or less |
Allowable 90 92 95 97 100 102 105 110 115 |
This material was produced under grant number 46C0D528 from the Occupational Safety and Health Administration, U.S. Department of Labor. It does not necessarily reflect the views or policies of the U.S. Department of Labor, nor does mention of trade names, commercial products or organizations imply endorsement by the U.S. Government.